<p>According to Joshua Bloch, author of "Effective Java":</p>
<blockquote>
  <p>The constant interface pattern is a poor use of interfaces. </p>
  <p>That a class uses some constants internally is an implementation detail.</p>
  <p>Implementing a constant interface causes this implementation detail to leak into the class's exported API. It is of no consequence to the users
  of a class that the class implements a constant interface. In fact, it may even confuse them. Worse, it represents a commitment: if in a future
  release the class is modified so that it no longer needs to use the constants, it still must implement the interface to ensure binary compatibility.
  If a nonfinal class implements a constant interface,</p>
  <p>all of its subclasses will have their namespaces polluted by the constants in the interface.</p>
</blockquote>
<h2>Noncompliant Code Example</h2>
<pre>
interface Status {                      // Noncompliant
   int OPEN = 1;
   int CLOSED = 2;
}
</pre>
<h2>Compliant Solution</h2>
<pre>
public enum Status {                    // Compliant
  OPEN,
  CLOSED;
}
</pre>
<p>or</p>
<pre>
public final class Status {             // Compliant
   public static final int OPEN = 1;
   public static final int CLOSED = 2;
}
</pre>

